When to Plant: Sweet peas can withstand light frosts, therefore in cold winter regions, sow in seed starting pots in early spring approximately 6-7 weeks before the final day of frost. Then, plant out as soon as the soil can be handled.
Sweet pea seeds can be directly placed into the garden in the fall from September to November in mild winter settings where the ground does not freeze. This will allow the seeds to develop healthy root systems and bloom in the spring.
If you give your seeds a head start by sowing indoors in seed containers from late January through March and transplant into the garden as soon as the soil can be worked, you can still receive a decent harvest of sweet peas, even though they will bloom a bit later. Sweet peas can handle light frosts.
1. Before planting, you could decide to nick your sweet pea seeds. The seed’s outer layer can be broken off by giving it a quick cut with a nail clipper so it can quickly absorb water. This will result in a higher percentage of your seeds germinating and a few days earlier sprouting.
This is how: Between your thumb and forefinger, hold a seed. Clip your seed by holding the clippers at an angle with the other hand so that you can only utilize the tip of the blade. Not taking a chunk out of the seed is your goal; it is to slice through the brown top layer of the seed. Sometimes the nick you caused is barely visible, and other times a bit of the seed coat cracks off revealing the interior seed’s lighter color. Both are true.
2. Avoid using garden soil when planting sweet peas in containers. Use high-quality potting mix instead. Using garden soil can lead to issues like compaction and poor drainage, whereas potting mix recipes are designed to perform under the circumstances found in a small container. In garden centers, a variety of soil mix brands are easily accessible.
Before filling your container, always pre-moisten your potting mix. As you slowly pour water into a bucket or wheelbarrow and stir the dirt, the earth will become evenly moist. When it feels like a wrung-out sponge, you are finished.
A 3 to 4 inch container works well for starting sweet peas. To prevent spreading disease to your new soil mix, properly clean the pot before using it again. After adding the pre-moistened mixture to the pot, give it a quick tap on the work surface to settle the soil. When a pot is filled correctly, the soil surface will be about 1 inch below the container’s top.
3. The time has come to plant your seeds. It matters how deeply you plant them. Always adhere to the planting depth recommendations on your packet’s back. Make a hole that is 1 deep for sweet peas. For this, a pencil or your finger works great.
4. Insert the seed into the opening you created. In order to ensure that every pot eventually gets a plant, even if one seed does not germinate or dies, we advise sowing two seeds each pot.
If you decide to plant 2 seeds per pot, you will need to thin them after the first set of leaves appear to 1 seedling per pot. At the soil line, trim or pinch out any surplus seedlings. Pulling it out could damage the surviving seedling’s roots, so avoid doing so.
5. Cover your seed with soil mixture after sowing. To remember what you planted when and how much of it, we advise labeling your containers with the variety and the date.
6. Lightly mist the seeds you covered. Use a watering can or hose with a diffuser attachment to let the water fall gently like rain. This will stop the water from washing the dirt away or compacting the soil too much.
Create the ideal circumstances for germination as you wait for your seedlings to appear. The two most critical variables are water and temperature. Your soil should always be damp, but not drenched. The ideal soil temperature is between 55 and 70 °F. You can start your seeds outside if the weather permits. A greenhouse or your home must be used to start them otherwise. Provide protection from birds, snails, and slugs if beginning them outside.
You must give your seeds a decent source of light once they have sprouted. If you want to keep them inside, you can put them beside a window as long as the sun won’t make them too hot during the day. Sweet peas do not have an issue with cooler nighttime temperatures near a window. Another option is fluorescent lighting. However, for the intensity to be bright enough, plants should be placed between 6 and 12 inches from the lights.
7. If you started your seeds indoors, the seedlings must be hardened off before being transplanted into your garden. Hardening off is the process of gradually exposing your plants to the elements they will experience outside, with temperature and direct sunlight being the most important factors. If you don’t, your seedlings can have transplant shock once they are planted in the garden.
When your plants have around 3–4 pairs of leaves, you can begin the hardening off procedure. Place your plants outside where they will receive morning sun in full force and afternoon shade. If you don’t have access to such a place, you will need to relocate your plants every day so that they are in the morning sun and out of the afternoon sun. Move them to a location where they will receive direct sun all day after about 3–4 days. You can move them into your garden in a few more days.
8. You can pinch or chop off the top of your seedlings when they have 3–4 pairs of leaves, leaving 2-3 pairs of leaves. Your cut should be made just above two leaves. By encouraging lateral branching, pinching helps you grow plants that are fuller.
9. Since sweet peas require healthy, well-drained soil, add some aged manure or other finished compost into your garden bed before planting. Work the material into the soil and rake the bed to level it out.
To move your seedling, make a hole that is both deep and wide enough to accommodate the root ball.
10. Try to minimize root disturbance while transferring your sweet pea seedlings from their container. Try it. Put one hand over the top of the pot, the seedling in your fingers, and flip the pot over to grab the root ball. Using the other hand, gently touch the bottom of the container while squeezing the edges to release the soil and plant.
11. Insert your seedling into the resulting hole, then cover it with soil. It is crucial when transplanting sweet peas that the soil level remain the same as it was in the pot. The plants may become sickly, stunted, or even die if you bury too much of the stem.
12. Leave 5 to 6 feet between each transplant. Your mature sweet peas’ health depends on the proper spacing between plants. Additionally, it provides the roots of individual plants with enough room to forage for water and nutrients while also enhancing air circulation to help avoid disease.
13. Gently water in your seedlings as soon as you are done transplanting. In addition to giving the plant water, this settles the garden soil around the root ball to prevent huge air pockets from drying out the roots. Use a watering can or hose with a diffuser attachment to water your plants, which will make the water fall gently like rain instead of washing the dirt away or beating your tender seedlings.
Tall sweet peas require a sturdy support in order to ascend. Build one now so that it is there when your seedlings are prepared to begin climbing.
14. You must keep birds, snails, and slugs away from your sweet pea seedlings. In order to prevent these typical predators from discovering your sprouts and eating them before you even realize they are up, you should do this as soon as possible after sowing your seed.
Use netting for birds. We create our own support hoops out of polytube, which is a flexible, black plastic irrigation tube that is sold at most reputable garden centers. It should be cut into lengths that correspond to the width of your garden beds. To create arches over your sweet pea bed, bury the ends of the cut tubing in the ground. These arches should be covered with bird netting, which should be secured at all edges to prevent openings. Before your sweet peas grow large enough to attach themselves to the netting, remove it. We choose the product Sluggo for snails and slugs because it is safe for use on people, pets, and wildlife.
15. You might want to assist stray branches in locating their vertical support structure as your plants grow higher and begin to climb. Encourage them to cling to you gently. Branches of sweet peas quickly break.
16. We advise deadheading to prolong the blooming period of your sweet pea plants. This entails removing wasted flowers before they have an opportunity to use their energy to produce seeds rather than other blossoms. Deadheading is best done right when the bloom has peaked and is just starting to fade. Cut the entire flower stem off at all times.
17. The blossoming of this plant is fully complete. When you can see, the plants begin to slow down and eventually stop flowering altogether as the discarded blooms turn into seedpods. Whether you deadhead or not, all sweet pea plants eventually reach the end of their flowering season. However, you can extend the bloom time by removing spent blossoms.
18. The flowers are, of all, the whole reason of producing sweet peas. Don’t forget to frequently clip them and bring them inside. They create lovely bouquets with the most amazing scents. Additionally, the plant will produce more blossoms the more you cut!
How long does it take for peas to harden?
The process of hardening off typically takes one week, but it can take as long as two weeks if the weather experiences an unexpectedly sharp drop in temperature.
If your area experiences frost, start your seeds in the spring so the seedlings can begin to be transplanted outside after the final frost date. (To get a specific sowing and transplanting timetable for your zip code, use my planting calendar.)
Before you begin hardening off leafy greens and other cool-weather plants, wait until the overnight lows are consistently in the 50s, or the high 50s for warm-weather plants like tomatoes, peppers, and squash.
However, they will need some form of frost protection at night, such as frost covers, cold frames, cloches, or unheated greenhouses. In rare circumstances, you can begin to harden off seedlings early.
How can you prevent leggy sweet peas?
Place your wigwam frame in a well-lit area where you can easily access flowers.
If planting sweet pea seeds sounds like too much work, you can always get sweet pea plug plants to get a head start. Due to the fact that slugs adore the young, new shoots, set them somewhere bright and keep an eye out for them.
Your seedlings will start to grow tall and lanky as they mature. Pinch out the plant’s tips to induce the production of side branches. Simply use your fingers to cut off the stem’s top just above a group of leaves. Each plant will become much bushier and stronger as a result. Additionally, the plant will produce more blossoms the more shoots there are!
How are sweet peas dried?
As soon as the sweet peas’ brittle, brown shells appear, start preserving the seeds. Sweet pea seedpods won’t germinate if you harvest them before they are fully developed. However, if you wait too long, the fragile seed pods will crack open and scatter their seeds all over the place. The procedure may take a few weeks, so keep an eye on them. You need to immediately pluck the pods if they start to split.
Sweet pea seeds are simple to collect. Remove the seeds from the seedpods and bring the plant inside. The seeds should dry for about three days on a level surface, such as a countertop or baking sheet, lined with newspaper. Once they are dry, store them to maintain their dryness in a freezer bag or Mason jar with a tight-fitting lid. Before planting, keep them in a cool location.
What happens if plants aren’t hardened off?
Plants that are started indoors are not yet prepared to be exposed to wind or sunlight, so we harden them off. Similar to us, plants must gradually increase their exposure to sunlight otherwise they will burn.
The sensitive plants will be scorched by the sun, the cold shock, or the wind if you don’t harden your plants. Even while some plants may fully recover from burns, their growth will be delayed for a few weeks.
How to Harden Plants
Plants should be placed outside for a few hours on the first day and brought inside at night to harden. Increase the amount of time they spend in the light each day until, after three or four days, you can keep them outside all night.
Plants can be hardened off on days that are partly cloudy. On the first day, if it’s a hot day, place them in the shade, ideally in part shade. On a sunny day, it is a good idea to shade the plants with Reemay cloth or floating row cover.
For a little extra protection
Try out this ruse! Remove the bottom of a gallon milk jug, place it over your new transplant, and bury it about 1 inch deep in the ground. When you water the plants, don’t forget to remove the jugs; instead, water each plant through the hole in the top of the jug.
How are sweet peas hardened in the UK?
All enthusiastic gardeners hear the call of spring in the late winter, and we rush outside to the garden. Then it starts to snow or the ground freezes, which means we have to start rearranging the potting shed again, which was not at all what we had in mind. So, rejoice that sweet peas exist. They can not only be sowed in the early spring, but they will also thrive if planted then.
Large roots are required to support perfect sweet peas. The deeper the pot, the better because chilly days will slow down top development while the roots silently expand.
How to sow sweet peas
Whether sweet peas need to be chipped and soaked before planting is a topic of discussion when thinking about how to seed them. At Easton, we only employ these methods when a given batch is obstinately failing to germinate.
A robust outer layer will develop to protect the seed in some years. Water has a hard time penetrating here, thus germination won’t start until it does. To avoid this, soak the seeds for a few hours prior to planting, or use sandpaper to remove portion of the outer covering off the side of the seed that is farthest from the eye.
Whatever you choose, sweet peas should be planted in moist seed compost at room temperature inside a propagator or indoors. To maintain effective drainage and lessen the possibility of the seeds decaying, incorporate sand into the compost. To keep mice out, cover the pots.
Hardening off sweet peas
It’s time to practice some tough love as the shoots start to appear. This entails escorting them to a protected area outdoors. They might be sitting on a garden table outside if you are near the southern coast. The optimum location will be a porch, cold frame, or unheated greenhouse further north.
Do not hasten the process of hardening off. Put the tiny seedlings outside during the day for a few days. Then decide on a gentle spell to begin permanently excluding them.
Alternative plans, like bringing them inside at night or adding heat to a greenhouse, will be necessary if the weather changes and the temperature routinely falls below freezing.
Pest control for sweet peas
Make sure to prepare ahead of time to keep mice away from the sweet peas before you move them. Although slugs are less of a threat to your entire crop, it is still a good idea to keep a look out for them.
Sweet peas should be planted on boards that have been set flat on concrete blocks, according to Roger Parsons, owner of the National Collection of Sweet Peas. Although the ice is a good climber, it cannot hang upside down, so make sure there is a significant overhang between the blocks and the edge of the plank.
To keep pests out, Easton uses a product line called Rootrainers. On hot days, the lids must be taken off to prevent scorching and to let air to circulate among the leaves.
Pinch out sweet pea leaves
This time of year, when temperatures can vary greatly, it is a good idea to pinch out the top leaves of your seedlings if they are growing in a triffid-like manner. Lower on the plant, new growth will emerge from the leaf axils, buying much-needed time until the seedlings are prepared for planting.
Plant out sweet peas
When weeds begin to sprout, brave gardeners can plant out hardened off sweet peas. This usually serves as a solid indicator of the likelihood of success for hardy annuals. Alternately, when the weather is erratic, be sure to check the soil’s temperature first. Plant them confidently if it doesn’t feel cold to the touch.
Recommended sweet pea cultivars
At Easton Walled Garden, we plant more than 100 different kinds of sweet peas every year. Some are infamously unstable, losing their best qualities over time. However, well chosen cultivars can resist the genetic urge to revert to the species type.
- Grandifloras with strong scents that date back to the turn of the 20th century are worth cultivating. Consider the rich blue “Lord Nelson” or the vivid cerise “Edward VII.”
- Because producers save their best varieties for these names, other sweet peas with patriotic names and those with aristocratic associations are frequently good choices. Try the color-changing mauve “Duchy of Cambridge” or the delicate lavender “Chatsworth” for contemporary variants. An alternative is the deep red “Sir Winston Churchill,” which is an older but still dependable shape.
- We adore “Albutt Blue” and “Duo Salmon” if you’re seeking for interesting colors with plenty of fragrant blossoms. When these two types are grown together, there will never be a shortage of cut flowers or admiring glances.
VisitAston.co.uk’s online store offers more than 75 uncommon sweet pea types and mixtures that can be grown from seed.